The present invention is directed to a tool chuck for holding the shank ends of tool bits in which at least one axially extending groove is located with the groove closed at the ends spaced apart in the axial direction. The tool chuck has a locking element as well as an entrainment strip for engagement within the groove. The locking element and entrainment strip are mounted in and are radially displaceable relative to a guide tube by an axially or rotatably adjustable adapter sleeve.
Tool bits for manually operated hammer drills and the like are known which have only axially extending groves closed in the axial direction. In the tool chuck disclosed in DE-OS 1 652 684, cylindrically shaped locking elements are provided in the chuck for engagement into closed ended axially extending grooves in the tool bit. Such locking elements serve to transmit torque from the tool chuck to the inserted end of the tool bit and also for axial retention of the tool bit in the tool chuck.
Further, in DE-OS 2 551 125 there are known tool bits with the insertion shank end formed with closed ended axially extending grooves and with axially extending grooves open at the trailing end. Locking elements engage in the closed ended grooves while entrainment strips engage into the grooves open at the trailing end with the locking elements and the entrainment strips positioned in the tool chuck. The locking elements serve only for axial retention of the tool bit with the transmission of rotary motion taking place via the entrainment strips.
Users of hammer drills and similar tools face the disadvantage in these different types of chucks in that the tool bit with an insertion shank end compatible with one type of chuck can only have limited use in tool chucks of the other type. While tool bits with closed ended axially extending grooves and axially extending grooves open at the trailing end can be used in tool chucks containing only locking elements, tool bits with only closed ended axially extending grooves cannot be utilized in most tool chucks containing both locking elements and entrainment strips.